Medical professionals commonly use catheters for gaining prolonged access to an area within the body. Once the catheter tip is positioned at the target location, treatments such as antibiotics, chemotherapy, pain medicine, and nutrition can be administered. However, if the catheter tip is improperly positioned during insertion, or if the catheter tip migrates out of position after insertion, various risks arise, including a fluid infusion that causes pain or injury to the patient, complications due to increased thrombosis rates, delays in therapy, catheter malfunction and additional costs.
The general standard for proper catheter insertion depends on the type of catheter and the type of treatment. For example, peripherally inserted central catheters (or PICC lines) are commonly inserted into a brachial, cephalic or basilic vein in the arm and advanced through the venous system towards the superior vena cava. Current medical standards recommended that the distal tip of the catheter terminate in the lower ⅓ of the superior vena cave, close to the junction of the superior vena cave and the right atrium. However, since PICCs are commonly inserted into a vein in the arm and advanced through the venous system to reach the superior vena cave, the PICC line tip may be inadvertently positioned in a non-target area, such as the internal jugular or subclavian vein. Further, even if a PICC is property inserted, the catheter tip could later shift out of position if for example the patient coughs violently, moves a lot, or experiences severe vomiting.
Catheter tip location techniques have improved the ability of medical professionals to verify the location of the catheter tip. One technique uses fluoroscopy to confirm tip location. Fluoroscopy provides the operator with real-time images of the patient's anatomy using a fluoroscope. Another technique uses electromagnetic detection and a stylet having an electromagnetic sensor placed inside the lumen of the catheter tip. Electromagnetic systems use an external device positioned directly over the internal target area for generating a magnetic field outside of the body. The electromagnetic sensor on the stylet is then inserted into the body through the catheter lumen and measures when the magnetic flux is at its greatest. A monitor indicates to the user when the electromagnetic sensor on the stylet is centered underneath the external device. In a variation of this technique, the external device senses the electromagnetic field. Electrocardiogram technology is also used determine catheter tip location by measuring the change of the P wave as the catheter progresses down the superior vena cave.
U.S. Pat. No. 5,161,536 issued to Vilkomerson at al. disclose an ultrasonic imaging system employing a processing circuit which enables the imaging system to accurately display the location of an element in a body by utilizing a transducer which provides an electric signal when an ultrasonic wave impinges thereon. The electric signal is processed to determine the maximum amplitude signals during an entire frame of the ultrasonic imaging system. The signals are characterized in terms of the line at which the signal appears or the ray at which the signal appears and the pixel or location along that line. The information regarding ray and pixel serves as X-Y coordinates enabling one to accurately locate the element and transducer on the displayed image by intensifying the display at that location or by adding color or by producing some other visual effect such as blinking, and so on.
There is a need for further methods, assemblies, and devices for positioning a catheter tip within a human body.